This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Human reproduction is inefficient with less than one-third of fertilized human eggs likely to survive to produce a term delivery. The great majority of these failures occur in the early weeks after ovulation. The causes of these reproductive failures are substantially unknown, but evidence suggests that they may be a consequence of maternal exposures, including pre-conception nutrition, that may result in insults to the oocyte and periconceptual embryo. The goal of this prospective epidemiologic study is to evaluate the hypothesis that dietary patterns associated with increased oxidative stress result in delayed time-to-pregnancy or early loss. Reactive oxygen species (ROS) have been associated with spontaneous abortion, preeclampsia, and premature preterm rupture of the membranes in women and defective sperm function in men. ROS are formed continuously as a consequence of both biochemical reactions and external factors. We propose to conduct a cohort study of 100 healthy women planning pregnancy. The outcomes to be evaluated are time-to-pregnancy, defined as the number of menstrual cycles from the cessation of contraception to a clinically recognized pregnancy, and early, unrecognized pregnancy loss. Unrecognized pregnancy and subsequent early loss will be determined by measuring urinary human chorionic gonadotropin (hCG). Diet will be assessed prior to conception using diet records and serum assays for the antioxidant vitamins C and E, and the carotenoids. Two urinary biomarkers of oxidative stress, 8-hydroxy-2'-deoxyguanosine and F2[unreadable]-isoprostanes will be measured.